Margaret Hilda Thatcher, Baroness Thatcher was a British stateswoman who served as Prime Minister of the United Kingdom from 1979 to 1990 and Leader of the Conservative Party from 1975 to 1990. She was the longest-serving British prime minister of the 20th century and the first woman to hold the office. As prime minister, she implemented policies that came to be known as Thatcherism. A Soviet journalist dubbed her the "Iron Lady", a nickname that became associated with her uncompromising politics and leadership style. Born: October 13, 1925 Died: April 8, 2013 In office: May 4, 1979 – November 28, 1990 Wiki link